The present invention relates to ink jet recording apparatus provided with a recording head for ejecting ink drops in accordance with print data. More particularly, the invention relates to a management technique which solves a problem arising from executing a flushing operation to idly eject ink drops to a capping member for hermetically closing a nozzle formation face of the recording head, and which suppresses the solidification of the ink and the like within the capping member by appropriately managing a flushing amount.
Generally, the ink jet recording apparatus is provided with the ink jet recording head for receiving ink from ink cartridge, and a sheet feeder for moving a recording sheet of paper relative to the recording head. An image is recorded on the recording sheet in a manner that ink drops are ejected onto the recording sheet in accordance with print data while moving the recording head in the main scanning direction. In the recording head, to print, ink is pressurized within a pressure generating chamber and ejected in the form of ink drops onto the recording sheet through the nozzle orifices. Therefore, the nozzle orifices are frequently clogged, and this results in improper printing. Various causes of the nozzle clogging exist, and examples of them are increase of ink viscosity due to solvent evaporation through the nozzle orifices, ink solidification, dust adhesion to the orifices, and entering of air bubbles.
To avoid the clogging trouble, this type of the ink jet recording apparatus uses a capping member for hermetically closing the nozzle formation face of the recording head in a non-print mode. The capping member serves as a lid for preventing the ink at the nozzle orifices of the recording head from being dried. Further, it serves to recover the ink drops ejection ability of the recording head. That is, when the nozzle orifices are clogged, the nozzle formation face is sealed with the capping member, a negative pressure is applied from a suction pump to the clogged nozzle orifices to forcibly suck the ink therefrom. In this way, the clogging of the nozzle orifices is removed.
A process of forcibly sucking the ink from the clogged nozzle orifices, which is executed for removing the clogging of the recording head, is called a cleaning operation. It is executed when the printing is started again after a long power-down time of the apparatus or when the user recognizes printing failure and operates a cleaning switch, for example. In the cleaning operation, under negative pressure generated by the suction pump, the ink is sucked into the capping member from the recording head, and then the nozzle formation face is wiped out with a wiping member formed of a rubber material, for example.
A drive signal, which is not related to the printing, may be applied to the recording head, thereby causing the recording head to eject ink drops. This operation is called a flushing operation. Uneven meniscuses at the nozzle orifices of the recording head are reshaped into the original states through the wiping operation by the wiping member. In the nozzle orifices which are infrequently used for ejecting ink drops during the printing operation, the ink located thereat is likely to increase its viscosity. Accordingly, those nozzle orifices are frequently clogged with the ink of increased viscosity. To avoid this, it is periodically executed.
Meanwhile, the flushing operation is executed to prevent the nozzle orifices having a less chance of ejecting ink drops during the printing operation from being clogged, as mentioned above. Additionally, it is executed for preventing the nozzle orifices from being dried when the recording head is out of operation by moistening the ink absorbing member located within the capping member with the ink.
Recently, the printing has been diversified, and use of the ink containing pigment is a trend in this field. Further, a technique also exists which adds surfactant to the ink composition in order to quicken the fixing of the pigment onto the recording sheet. In the pigment contained ink, a problem that bubbles are generated in the capping member arises. The generated bubbles will destroy the meniscus formed at the nozzle orifices, so that ejection failure occurs. A possible means to avoid the printing trouble of the recording head owing to such ink bubbles is to deepen the capping member to have the deep inner bottom part so that the ink bubbles are away from the nozzle formation face.
In a case where the capping member having the deep inner bottom part is employed, the following problems arises anew. When the flushing operation is executed, ink drops ejected from the nozzle orifices are impeded by air resistance and the like during their flight, and transformed into finer ink drops (ink mist) since a distance between the nozzle formation face and the bottom part of the capping member is large. The ink mist tends to leak out from the space defined between the nozzle formation face of the recording head and the capping member, and floats within the recording apparatus.
The ink mist floating within the apparatus stick to the guide rod for moving the carriage or the like, soils the same, thereby making the carriage movement difficult. Further, the ink mist soils other mechanisms. As a result, the normal operation of the recording apparatus is lost. The ink mist also soils the recording sheet under printing.
A specific color ink of the pigment-contained ink is easy to solidify at a specific position within the capping member, through the repeated flushing operations. In an extreme case, the solidified ink is accumulated into a mountain-like shape. When the recording head is sealed with the capping member, there is a chance that the accumulated ink reaches the nozzle formation face.
The present invention is directed to solve the problems arising from the flushing operation, and has an object to provide an flushing control method which selects an operation mode to execute a flushing process in a state that the nozzle formation face of the recording head is sealed with the capping member in particular when a flushing amount is large, and solves the problem of the accumulation of the solidified specific color ink, and ink jet recording apparatus which guarantees a high print quality for a long time.
In order to achieve the above object, there is provided an ink jet recording apparatus, comprising:
an ink jet recording head, provided with a nozzle formation face on which nozzle orifices for ejecting ink drops in accordance with print data are formed;
a capping member, which seals the nozzle formation face, the capping member having an inner space formed with a bottom;
an ink absorbing member, provided on the bottom of the inner space in the capping member;
a first flushing mode, in which ink drops are ejected into the capping member in a state that the nozzle formation face is sealed by the capping member; and
a second flushing mode, in which ink drops are ejected into the capping member in a state that the capping member is separated from the nozzle formation face,
wherein either the first flushing mode or the second flushing mode is selectively performed.
Preferably, the number of ink drops ejected in the first flushing mode is greater than the number of ink drops ejected in the second flushing mode. In other words, when the first flushing mode is selected which is executed in a state that the nozzle formation face of the recording head is hermetically closed with the capping member.
In this configuration, the ink mist generated in the flushing operation is remarkably reduced, even if a distance between the nozzle formation face and the ink absorbing member is made large.
Preferably, ink drops are ejected while varying a distance between the nozzle formation face and the ink absorbing member in accordance with a kind of ink ejected, when the second flushing mode is performed.
In this configuration, generation of the ink mist by the specific ink which is easy to generate ink mist is effectively suppressed.
Preferably, ink drops of different kinds of inks are ejected so as to land on a substantially identical position on the ink absorbing member, when the second flushing mode is performed. Here, it is preferable that ink drops of a first kind of ink which is easy to solidify are first ejected, and then ink drops of a second kind of ink which is hard to solidify are ejected.
In this configuration, the accumulation of the solidified ink is remarkably reduced. In other words, the technical feature successfully solves the ink solidification and accumulation problem, which arises from the fact that the flushing operation using a small amount of ink is frequently performed at substantially the same position of the ink absorbing member.
Preferably, the number of ink ejected is varied in accordance with a kind of ink ejected, when the first flushing mode and the second flushing mode are performed.
In this configuration, the ink being easy to increase its viscosity at the nozzle orifices can be positively discharged. Accordingly, the running cost of the recording apparatus on the ink consumption is reduced when comparing with the recording apparatus in which the number of ejecting operations is set at a fixed value for every kind of ink.
Preferably, the recording apparatus further comprises: a flushing amount counter, which counts an accumulated number of ink drops ejected when the first flushing mode and the second flushing mode are performed; and a suction member, which is communicated with the inner space of the capping member to suck ink therein. Here, the suction member performs an idle suction, in which a part of ink absorbed in the ink absorbing member is sucked while the capping member is separated from the nozzle formation face, when the flushing amount counter counts a predetermined value.
Here, it is preferable that the flushing amount counter is reset when the suction member performs the idle suction.
Here, it is preferable that the second flushing mode is performed at least one of when: every time when a first time period is elapsed; and a recording paper is discharged from the apparatus. On the other hand, the first flushing mode is performed at least one of when: every time when a second time period which is longer than the first time period is elapsed; a power-off instruction of the apparatus is issued; and a recording paper is discharged from the apparatus.
According to the present invention, there is also provided a flushing control method for the above ink jet recording apparatus comprising the steps of:
counting an accumulated number of ink drops ejected;
judging the accumulated number reaches a predetermined value;
performing an idle suction, in which a part of ink absorbed in the ink absorbing member is sucked while the capping member is separated from the nozzle formation face, when the accumulated number reaches a predetermined value; and
resetting the accumulated number when the idle suction is performed.
Preferably, the method further comprises the steps of: counting a first time period; and performing the second flushing mode every time when the first time period is elapsed. Here, the accumulated number counting step includes the step of counting the number of ink drops ejected when the second flushing mode is performed.
Further, it is preferable that the method further comprises the step of counting a second time period which is longer than the first time period. Here, the accumulated number judging step is executed every time when the second time period is elapsed.
Here, it is preferable that the method further comprises the step of performing the first flushing mode when the accumulated number does not reaches the predetermined value. The accumulated number counting step includes the step of counting the number of ink drops ejected when the first flushing mode is performed.
Further, the method further comprises the step of detecting whether a power-off instruction of the recording apparatus is issued. Here, the accumulated number judging step is executed when the power-off instruction is detected.
Here, it is preferable that the step of performing the first flushing mode when the accumulated number does not reaches the predetermined value. The accumulated number counting step includes the step of counting the number of ink drops ejected when the first flushing mode is performed.
Still further, the method further comprises the steps of: counting a second time period which is longer than the first time period; judging whether a recording paper is discharged from the recording apparatus; and judging whether the second time period is elapsed when the recording paper is discharged. Here, the accumulated number judging step is executed when the second time period is elapsed.
Here, it is preferable that the method further comprises the step of performing the first flushing mode when the accumulated number does not reaches the predetermined value. The accumulated number counting step includes the step of counting the number of ink drops ejected when the first flushing mode is performed.
On the other hand, it is preferable that the method further comprises the step of performing the second flushing mode when the first time period is elapsed but the second time period is not elapsed. The accumulated number counting step includes the step of counting the number of ink drops ejected when the second flushing mode is performed.
In the above configurations, an amount of ink that is ejected into the capping member by the flushing operations is managed by the flushing amount counter. The capping member is filled with such an amount of ink as to cover the ink absorbing member. Since a part of ink is subsequently sucked from the ink absorbing member by the suction member, the ink absorbing member is made sufficiently moist with the ink.
Accordingly, when the nozzle formation face is sealed during a non-print time of the recording apparatus, volatilization of the ink solvent through the nozzle orifice is suppressed with the ink in the sufficiently moist ink absorbing member. As a result, the increase of a viscosity of the ink or the solidification of the ink at and around the nozzle orifices are effectively suppressed.
Further, the easy-to-solidify ink and the hard-to-solidify ink are mixed through the execution of the above-mentioned control. Therefore, solidification and accumulation of the ink in the ink absorbing member can be prevented. The waste ink is swiftly discharged by suction member.